Generally, a heat exchanger as one of components for constituting an air conditioner for a vehicle is adapted to change the state of a heat exchanging medium or perform heat exchange of the heat exchanging medium with outdoor air, thus conducting cooling or heating.
The heat exchanger includes a pair of header tanks spaced apart from each other in parallel to each other, tubes each having both ends fixed to the header tanks to form a heat exchanging medium passage, and fins interposed between the tubes.
Each tube is made by means of extrusion and folding, and the methods for making the tubes are appropriately selected according to the specifications (sizes, weights, pressure resistances, and amounts of heat exchanging medium flow) required by the kinds of heat exchangers.
The method for making the tubes through folding provides better productivity than the method for making the tubes through extrusion, but has lower strength than that.
Further, the tube made through folding is disclosed in Japanese Patent Application Laid-Open No. 2005-214511 (entitled ‘heat exchanger’), which is shown in FIG. 1.
As shown in FIG. 1, a tube 5 for a heat exchanger is made of a plate 5a that has a clad material 5c applied to the external surface thereof in such a manner as to allow bonding portions 47 bent in the left direction of the tube 5 to be bonded to each other. Further, an inner fin 49 is made of a plate 49a that has clad materials 49b and 49c applied to both surfaces thereof in such a manner as to be bent in the internal space of the tube 5.
The conventional tube 5 as shown in FIG. 1 is reinforced in strength through the bonding portions 47 formed in the left direction thereof, but only the plate 5a for forming the tube 5 exists in the opposite side to the bonding portions 47, thus making it difficult to achieve good durability.
Particularly, if the heat exchanger is used as a condenser for a vehicle and the left and right portions of FIG. 1 collide against foreign materials, the left and right portions may be absolutely damaged, thus being exposed to the danger that the tube is broken.
To further meet the demand of today's miniaturization trends, the weight of the tube should be reduced, and accordingly, there is a need for the development of a heat exchanger capable of reducing an amount of materials used and providing sufficient durability.
Accordingly, the present invention has been made in view of the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a tube for a heat exchanger which has first reinforcement portions and second reinforcement portions formed on both end portions of an inner fin disposed in the internal space thereof, wherein the first reinforcement portions correspond to curved portions of the tube and the second reinforcement portions are bonded to the first reinforcement portions, thus increasing the strength on both end portions of the tube in an air flow direction of the tube.
It is another object of the present invention to provide a tube for a heat exchanger wherein the tube and an inner fin disposed inside the tube are made of thin plates, thus achieving high productivity, increasing strength, and providing good durability.